1. Field of the Invention
The present invention relates to holding tanks and more particularly to precast concrete holding tanks with an inlet for receiving materials into the tank, together with associated tank systems and methods of manufacture of tanks and tank systems.
2. Background Information
Holding tanks are commonly used in sewage holding and/or septic systems. Typically a sewage holding tank includes an inlet to receive the sewage and a manhole positioned at the top of the tank for access into the tank. A hose is usually connected to or placed within the tank to remove the sewage by pumping. Many holding tanks are made with concrete and are configured to hold several thousands of gallons. In some jurisdictions a 2000 gallon capacity tank is utilized or is the minimum capacity required. To achieve sufficient volume a typical tank will have a general dimension of 12 feet long by 8 feet wide by 5 feet tall. The tank will typically be buried in the ground and often a few feet of dirt or soil will cover the tank. The tank must be structurally sound to hold such large volumes of sewage while also being strong enough to support a covering of dirt or soil and to withstand breaking or cracking while also avoiding leaks. A typical tank also includes a pre-cast concrete cover which is placed on top of a pre-cast concrete box-like structure. A sealant such as liquid tar or other sealant is placed on the top of the walls of the box-like structure and the cover is then placed on the sealant. A problem occurs if the sealant releases or is compromised, such as in harsh conditions of freeze/thaw, where sewage may escape the tank or liquids may infiltrate the tank. Sewage escaping the tank may cause sanitary and environmental problems. Liquids seeping into the tank also cause the tank to fill prematurely, resulting in additional cost of having to frequently pump the full tank
These and other problems demonstrate there is room for improvement of holding tanks.